RU2499081C2 - Systems and methods to distribute gas in reactor for chemical deposition from steam phase - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: reactor for chemical deposition of polycrystalline silicon includes a reaction chamber, comprising a support board fixed in the reaction chamber, and a jacket connected to the support board for formation of the deposition chamber, a filament element attached to the support board, a source of electric current for supply of current to the filament element, a source of silicon-containing gas connected with the reaction chamber to create the flow of silicon-containing gas via the reaction chamber and the vertical pipe, connected to the source of silicon-containing gas, for introduction of the flow of silicon-containing gas into the reaction chamber. The vertical pipe is made as capable of receiving deposits of polycrystalline silicon in the reaction chamber.

EFFECT: improved flow of gas in all volume of a reaction chamber, which makes it possible to increase yield of polycrystalline silicon, improved quality of polycrystalline silicon and reduced energy consumption.

22 cl, 4 dwg

Description

CROSS REFERENCE TO A RELATED APPLICATION

This application claims the benefit of being pending U.S. Patent Application Serial No. 61/039758, filed March 26, 2008, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention is directed to systems and methods for producing materials such as polycrystalline silicon by chemical vapor deposition in a reactor. More specifically, the present invention relates to gas distribution systems and methods for improving flow conditions in a chemical vapor deposition reactor using a silicon vertical pipe.

BACKGROUND

Chemical vapor deposition (CVD) refers to reactions typically occurring in a reaction chamber in which solid material is precipitated from the gaseous phase. CVD can be used to produce high-performance, high-purity solid materials, such as polycrystalline silicon, silicon dioxide, and silicon nitride. In the manufacture of semiconductors and photovoltaic devices, CVD is often used to produce thin films and bulk semiconductor materials. For example, heated surfaces may be exposed to one or more gases. When gases enter the reaction chamber, they come in contact with heated surfaces. As soon as this happens, then reactions or decomposition of gases proceed with the formation of a solid phase, which is deposited on the surface of the substrate with the formation of the desired material. For this process, the gas flow regime is very important, which affects the speed with which these reactions will proceed and the quality of the products.

For example, in the chemical vapor deposition of polysilicon, polycrystalline silicon can be precipitated from silane (SiH ₄ ), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ) and tetrachlorosilane (SiCl ₄ ), according to the corresponding reactions. These reactions are usually carried out in a vacuum or in a CVD reactor under pressure using either pure silicon-containing raw material or a mixture of silicon-containing raw material with other gases. The temperatures required for the reaction range from hundreds of degrees Celsius to temperatures in excess of one thousand degrees Celsius. Polycrystalline silicon can also be grown directly doped by adding gases such as phosphine, arsine, or diborane to the CVD chamber.

Therefore, the gas flow regime is important not only for the growth of polycrystalline silicon and other materials, but also for influencing the performance, product quality, and energy consumption of the entire CVD reactor.

SUMMARY OF THE INVENTION

The present invention relates to systems and methods for distributing gas in a reactor for chemical vapor deposition, in particular, to improve the flow of gas in a CVD reactor. Thus, the present invention can be used to increase the efficiency of reactions inside CVD reaction chambers, increase the yield of solid precipitated product, improve product quality and reduce overall operating costs. The present invention also provides that silicon deposited on vertical tubes in a CVD reactor can be used as an additional polysilicon product.

In the reactor and method according to the present invention, in particular in the CVD reactor and method, a vertical pipe is used. A vertical pipe can be used to introduce a variety of reagents into the reaction chamber. The vertical pipe is preferably made of silicon or other materials. These materials, without limitation, include: metals, graphite, silicon carbide, and other suitable materials. The length of the vertical pipe can vary from about 1-2 centimeters up to about several meters, depending on the application. The diameter of the pipe can vary from about 1-2 millimeters to tens of centimeters, depending on the amount of gas flow. The wall thickness is preferably from about 0.1 to about 5.0 millimeters.

The reactor according to the present invention includes a reaction chamber having at least one support plate fixed inside the reaction chamber, and a casing operably connected to the support plate. One or more filament elements are attached to the base plate inside the chamber, onto which a variety of gaseous reactants are deposited during the chemical vapor deposition cycle. The filament element may be a silicon filament element or may be made of another desired solid material that is desired to be obtained. At least one gas inlet and one gas outlet are connected to the reaction chamber to allow gas to flow through the reaction chamber. An inspection window or porthole may also be provided for observing the interior of the camera. The electric current source is preferably connected to the ends of the filament element through electric leads in the base plate for supplying electric current to directly heat the filament element during the CVD reaction cycle. To reduce the temperature in the chemical vapor deposition system, a cooling system may also be used having at least one fluid inlet and at least one fluid outlet.

Preferably, the vertical pipe of the present invention is operatively connected to at least one gas inlet for introducing a gas stream into the reaction chamber. The vertical pipe preferably includes a connecting tip and a pipe body. The length and diameter of the pipe body can be selected based on at least the desired gas flow rate. The connecting tip may further include a sealing device, such as a gasket, for sealing the pipe body at least at one gas inlet. The vertical pipe preferably has at least one discharge pipe inside the chamber for distributing the flow of the working gas. The dimensions of the at least one discharge pipe are based on the desired flow rate. Silicon or another material may be selected as the material of the discharge pipe.

These and other aspects and advantages of the present invention will become more readily apparent from the following description of preferred embodiments given in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order for specialists in this field of technology, the competence of which the present invention is included, it was easy to understand how to implement the method and make the device for using the present invention without undue experimentation, the preferred options for its implementation will be described in detail below with reference to certain figures, in which:

1 is a perspective view of a reaction chamber system according to the present invention;

FIG. 2 is a perspective view of the inside of the reaction chamber of FIG. 1;

FIGA is an enlarged sectional view of a vertical pipe according to the present invention;

FIG.3B is a more detailed image of the connecting tip attached to the tubular casing of the vertical pipe of FIG.3A;

FIG.3C is an enlarged view of the gasket on the connection tip shown in FIG.3B; and

FIG. 4 is a partial cross-sectional view of a reaction chamber system according to the present invention, including numerous vertical pipes.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which like reference numerals represent the same or similar elements.

The present invention relates to systems and methods for distributing gas in a reactor, in particular for improving gas flow in a chemical vapor deposition (CVD) reactor. In particular, the present invention is directed to a system and method for distributing gas in a CVD reactor using a vertical pipe. Benefits and advantages of the present invention include, but are not limited to, increasing levels of productivity in producing solid precipitated material (e.g., polycrystalline silicon), lowering energy consumption, and lowering overall operating costs. While the description of the present invention is oriented to an exemplary CVD reactor system for producing polycrystalline silicon, the system and methods of the present invention can be applied to any CVD reactor for which it is desirable to enhance gas distribution and improve gas flow conditions, and to any reactor at all.

In an exemplary application, gaseous trichlorosilane reacts on rods or silicon tubular filament elements inside the reaction chamber to form deposits of polycrystalline silicon on thin rods or filament elements. The present invention is not limited to CVD reactors that use polycrystalline silicon deposition, including the trichlorosilane reaction, but can be used for reactions involving silane, dichlorosilane, silicon tetrachloride or other derivatives or combinations of gases, for example, using thin rods or incandescent elements, having geometric shapes with a large surface area and similar characteristics of electrical resistivity in accordance with the invention. Incandescent elements of various shapes and configurations can be used, for example, such as those described in Patent Application Publication US 2007/0251455, which is incorporated herein by reference.

With the involvement of FIGS. 1 and 2, a chemical vapor deposition (CVD) reactor is shown in which polycrystalline silicon is deposited on thin rods or incandescent elements according to the present invention. The reactor 10 includes a reaction chamber 12 having a support plate 30, a gas inlet tip 24 or a flange for working gases, a gas outlet nozzle 22 or an outlet flange, and electrical leads or conductors 20 for supplying current for directly heating one or more filament elements 28 inside the reaction chamber 12 as shown in FIG. 2. The tip of the fluid inlet port and the fluid outlet port 14 are connected to a cooling system for introducing the fluid into the reaction chamber 10. In addition, a porthole 16 or an inspection window preferably provides a visual observation of the inside of the reaction chamber 12 and optionally can be used for conducting temperature measurements inside the reaction chamber 12.

According to a preferred embodiment of the present invention, as shown in FIGS. 1 and 2, the reactor 10 is configured to produce bulk polycrystalline silicon. The reactor includes a base plate 30, which, for example, can be a single plate or multiple opposing plates, preferably arranged to support the filament elements, and a casing attached to the base plate 30 so as to form a precipitation chamber. As used herein, the term “jacket” refers to the interior of the reaction chamber 12 where a CVD process may occur.

One or more silicon filament elements 28 is preferably placed inside the reaction chamber 12 on supports of filament elements (not shown), and an electric current source can be connected to both ends of the filament elements 28 through electrical leads 20 in the base plate 30 for supplying current for direct heating of the filament elements. Additionally, at least one gas inlet tip 24 is provided in the base plate 30, connected, for example, to a silicon-containing gas source, and a gas outlet tip 22 in the base plate 30, by which gas can be removed from the reaction chamber 12.

FIG. 2 shows the structure of an exemplary vertical pipe 42, in which preferably the tubular body 44 is operatively connected to at least one gas inlet tip 24 for introducing various gases into the reaction chamber 12 for conducting a CVD reaction proceeding in the reaction chamber 12 (see also FIG.3A). Although in FIG. 2 depicts a single discharge pipe 42, one or more vertical pipes may be placed in the reaction chamber. For example, with the involvement of FIG. 4, a single vertical pipe can be replaced by vertical pipes 42. The dimensions of each vertical pipe or discharge pipe 42 can vary from about 1-2 cm in length up to several meters, and from about 1-2 mm in diameter up to tens of centimeters, depending on the desired configuration of the gas stream.

Preferably, one or more vertical pipes 42 are used to pump one or more gases into different parts of the reaction chamber 12, depending on the desired flow regime. The vertical pipe (s) 42 may be secured (s) in the reactor using any known mounting device, for example, by screwing the pipe body 44 into the connecting tip 25 of the reaction chamber 12 (see FIGURES 3A- 3C, as described here). Since flow conditions can be critical to growing, the level of productivity, product quality, and energy consumption for producing polycrystalline silicon, the present invention may be applicable to methods for producing polycrystalline silicon and any other methods that include deposition of silicon or a silicon compound. More specifically, it can also be applied in methods where corrosion, contamination, and deposition can occur on pipe and other forms of components.

Again with the involvement of FIGURES 3A-3C, the various components of the vertical pipe 42 are preferably made of a silicon pipe. Silicon is used as an alternative to non-silicon materials, such as stainless steel or other metals, which can cause corrosion, contamination, melting and unwanted deposition of silicon inside the pipe body 44. At one end of the pipe body 44, the material from which the pipe body 44 is made is welded with materials that may be machined. These materials include metals, graphite, silicon carbide and any other suitable material. At the other end, as shown in FIGS. 3A-3C, the pipe body 44 is preferably connected to a connecting tip 25 having an appropriate diameter. The connection tip 25 is preferably formed with a gasket 26 to provide an airtight seal between the gas inlet tip 24 and the gas source supplied to the vertical pipe. The length of the pipe body 44 may vary from about a few centimeters to about a few meters, depending on the application. The diameter of the pipe body 44 may vary from about a few millimeters to tens of centimeters, depending on the magnitude of the gas flow rate. The wall thickness of the pipe body 44 is preferably of the order of about several millimeters or less. The pipe body 44 is preferably made of silicon.

A method for depositing material in a reactor may include stages in which: providing a reaction chamber comprising at least one support plate fixed inside the reaction chamber and a casing operably connected to the support plate / insert at least one filament element into the support plate; connecting a source of electric current to the reaction chamber to supply current to the filament element; connecting a gas source to allow gas to flow through the reaction chamber; connect a vertical pipe to a gas source to distribute the gas stream inside the reaction chamber; and provide operation (exploit) of the reactor for the deposition of material on at least one filament element in the reaction chamber.

An additional advantage of the vertical pipe according to the present invention is that it can be reused or recycled for reuse. During the gas injection process, silicon is deposited on the pipe body 44. When the silicon layer builds up, silicon can be removed from the tubular bases and used as a silicon product.

Although the present invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that changes or modifications to it can be made without departing from the spirit and scope of the present invention as defined in the appended claims.

TURNING THE LINK ON

The full contents of all patents, published patent applications and other references cited herein are hereby expressly incorporated by reference in their entirety.

Claims (22)

1. A reactor for chemical vapor deposition of polycrystalline silicon, comprising a reaction chamber comprising at least one support plate fixed in the reaction chamber, and a casing connected to the support plate to form the deposition chamber, at least one filament element attached to a base plate, an electric current source for supplying current to at least one filament element, a silicon-containing gas source connected to the reaction chamber to create a silicon-containing stream of the gas through the reaction chamber, and a vertical tube connected to a source of a silicon-containing gas to enter the silicon-containing gas flow into the reaction chamber, wherein the vertical pipe is adapted to receive deposits of polysilicon in the reaction chamber. 2. The reactor according to claim 1, in which the current is supplied directly to the filament element through an electrical supply in the base plate. 3. The reactor according to claim 1, in which the reaction chamber further includes a viewing window for monitoring the inside of the reaction chamber. 4. The reactor according to claim 1, in which the vertical pipe is made of silicon. 5. The reactor according to claim 1, further comprising at least one additional vertical pipe introduced into the reaction chamber. 6. The reactor according to claim 1, in which the vertical pipe further includes a connecting tip and a pipe body, and the connecting tip is designed to connect to a source of silicon-containing gas. 7. The reactor according to claim 6, in which the diameter of the pipe body is selected based on at least the desired flow rate of the silicon-containing gas stream. 8. The reactor according to claim 6, in which the connecting tip further includes a gasket for sealing the vertical pipe with a source of silicon-containing gas. 9. The reactor according to claim 1, which is a reactor for chemical vapor deposition. 10. The reactor according to claim 1, further comprising a cooling system having at least one fluid inlet and a fluid outlet operably coupled to the reactor. 11. A method of chemical vapor deposition of polycrystalline silicon in a reactor, comprising the steps of providing a reaction chamber including at least one support plate fixed in the reaction chamber and a casing connected to the support plate to form the deposition chamber, at least one filament element to the base plate, an electric current source is connected to the reaction chamber to supply current to the filament element, a silicon-containing gas source is connected to the reaction a vertical pipe is connected to a silicon-containing gas source to distribute the flow of silicon-containing gas inside the reaction chamber, the vertical pipe being configured to receive polycrystalline silicon deposits in the reaction chamber, and the reactor is operated to deposit material on at least one filament element in the reaction chamber. 12. The method according to claim 11, in which the material deposited on the filament element is a polycrystalline silicon. 13. The method according to claim 11, in which the filament element includes silicon. 14. The method according to claim 11, in which the reactor is a reactor for chemical vapor deposition. 15. The method according to claim 11, further comprising a stage in which an electric current is supplied directly to the filament element through an electric supply in the base plate. 16. The method according to claim 11, in which the reaction chamber further includes a viewing window for monitoring the inside of the reaction chamber. 17. The method according to claim 11, in which the vertical pipe is made of silicon. 18. The reaction chamber of the reactor for chemical vapor deposition of polycrystalline silicon, containing at least one support plate fixed in the reaction chamber, at least one filament element attached to the support plate, and the reaction chamber is connected to an electric current source and a silicon-containing source gas to ensure deposition of the material on at least one filament element, and a vertical pipe attached to a source of silicon-containing gas to distribute sweat Single silicon-containing gas within the reaction chamber, the riser is configured to receive deposits of polysilicon in the reaction chamber. 19. The reaction chamber according to claim 18, wherein the electric current is supplied to the filament element using an electric current source. 20. The reaction chamber according to claim 19, in which an electric current is supplied directly to the filament element through an electric supply in the base plate. 21. The reaction chamber according to claim 18, further comprising at least one silicon-containing gas inlet and a silicon-containing gas outlet connected to the reaction chamber to create a silicon-containing gas stream through the reaction chamber. 22. The reaction chamber according to claim 18, further comprising a viewing window for monitoring the inside of the reaction chamber.

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